The industrial and commercial activities of modern businesses are characterized by the use of large and complex systems of various types. Chemical and manufacturing operations employ operating systems of various types in the manufacturing and environmental aspects of these businesses. For example, a chemical plant may require an operating system to direct the execution of various steps in the process necessary for the production of various chemicals. As the product, efficiency, and quality demands on these systems have become greater, the systems themselves have become much more complex.
To respond to this additional complexity, there has been an increasing tendency to rely on computer-based control of such systems' operation. The increasing power and reliability of small personal computers whose cost has drop steadily meanwhile has only speeded this transition. The use of computer control itself allows added complexity and speed in the operations involved, with the result that the humans responsible for these operations have become increasingly less able to determine directly their status.
It is axiomatic that it is necessary to analyze the operation of complex systems throughout their life. During installation, it is necessary to analyze operation in order to detect installation errors. During normal operation, it is necessary to monitor the processes involved in order to determine degradation and failures of individual components and flaws in both input and output product. If faults in operation are detected, then it is necessary to closely monitor the operation in order to efficiently and accurately sense the cause of the faulty operation.
This analysis typically is based on individual sensors or other indicators of the various aspects of the operations, and then the magnitude (or existence) of each condition is provided for the human operator. The human operator then could infer from these conditions what the status of operation is, and can take appropriate steps when problems are indicated.
Among the most important conditions which indicate system operation are simply the current and past operating states of the system. By the term "operating state" in this context is meant the particular phase or type of operation in which the system is engaged. The invention to be described was developed for the purpose of controlling the operation of large burner systems, and for this reason it is convenient to explain operating states of a typical operating system and the invention itself in relation to burner systems.
In burner systems, the standby state is one operating state, and indicates the burner is idle, not providing heat for the process or space. A normal operating sequence is initiated when there is a demand for heat. In the first operating state, the burner enters a purge phase where a blower forces air through the combustion chamber to assure that the blower is operational and there are no combustible vapors in the chamber. From the purge state, the burner enters an ignition operating state where the igniter is enabled. After the igniter has been enabled, then the burner enters its pilot state where the pilot fuel valve is opened, and the pilot flame is established. Once the pilot flame is established, the igniter is disabled. Then the main valve is opened, and for a period a pilot and main operating state exists. Then the pilot valve is typically closed, and the main only operating state is entered. After the demand for heat has been satisfied, the main valve is closed, and the blower is allowed to run for a further period, which forms a second purge operating state. After the second purge state is complete, then the system returns to the standby operating state. If any malfunctions occur during this sequence, these create other operating states as well. Thus it can be seen that for even a simple large burner system a number of different operating states can exist.
For a number of reasons, simple visual inspection of operating systems such burner systems is ineffective in determining operating states. Where systems are physically large, a number of tours of the system are necessary to determine the operating states. The operator will be able to gain only a rough idea of when a particular operating state ends and another begins. Where there are a large number of operating states, it becomes laborious to track and record the operating states. Where individual operating states are of short duration, visual inspection of the system and gauges may not detect their existence. If a combination of conditions are necessary to constitute an operating state, (such as the main and pilot valves both open) it may be complicated to determine. In other cases, the timing or phasing of changes in indicators is the important factor in establishing presence of a fault. Even if phasing of indicator changes is not important in determining the presence of a fault, phasing may still be important in diagnosing the cause of a fault. Further, changes in phasing may indicate deterioration of particular system components, whose early detection allows correction during routine maintenance, or at least allows avoiding expensive failure during operation, where damage or injury may occur.
Accordingly, some way of collating or collecting these indicators and presenting them in a way which is instantly understandable and useful is extremely desirable.